1. Field of the Invention
The present invention relates to an electronic circuit analyzing apparatus used to check the operations of an electronic circuit, an electronic circuit analyzing method, and an electronic circuit analyzing program.
2. Description of the Related Art
As electronic circuits such as LSI (Large Scale Integration) systems, PCBs (Printed Circuit Boards), and multichip modules, for example, have increased in speed in recent years, analytic models used for signal waveform analysis have come to exhibit considerable variation depending on the frequency. As a result, determining the kind of input information to be used to create an analytic model has become important.
Moreover, since noise margins have decreased in conjunction with the development of low-power electronic circuits, it has become necessary to design electronic circuits in consideration of signal waveform variation caused by manufacturing irregularities in the element and electrical board, voltage fluctuation of the power source or ground, and so on.
The constitution of a conventional electronic circuit analyzing apparatus will now be described. FIG. 9 is a block diagram showing an example of the constitution of a conventional electronic circuit analyzing apparatus. This electronic circuit analyzing apparatus is constituted by an input information storage unit 1, an analytic model creation unit 2, an analysis unit 3, an analysis result determination unit 4, and a display unit 5.
The input information storage unit 1 stores analysis conditions, layout data, element model data, and parameter data, which are used in an electronic circuit simulation, as input information. Here, the analysis conditions include the analysis frequency, the analysis time, and so on. The layout data are data used when designing the electrical board layout. The element model data describe the electrical characteristics of the element in a predetermined format. The parameter data are analysis parameters relating to the material, form, and so on of the electrical board.
The analytic model creation unit 2 creates an analytic model to be used in a simulation from the input information stored in the input information storage unit 1, and outputs the analytic model to the analysis unit 3. The analysis unit 3 performs a simulation using the analytic model, and outputs waveforms calculated at arbitrary measurement location positions on the electronic circuit to the analysis result determination unit 4 and display unit 5 as the analysis result. The waveforms express temporal transition in the voltage value, for example. The analysis result determination unit 4 determines whether the analysis result is good or bad using a predetermined condition, and outputs “good” or “bad” to the display unit as the determination result. The predetermined condition is a input voltage range value on an element data sheet or the like, for example. If there is more than one analysis result, the analysis result determination unit 4 performs a plurality of good/bad determinations.
When, for example, the analysis result is a voltage waveform, and the determination threshold is a maximum input voltage range value, the determination result is good if the peak value of the voltage waveform is equal to or less than the maximum input voltage range value, and bad if the peak value of the voltage waveform exceeds the maximum input voltage range value. When the determination threshold is VIH (minimum High-level input voltage), the determination result is good if the voltage waveform in the analysis result exceeds VIH when High is expected, and bad if the voltage waveform is equal to or less than VIH.
The display unit 5 displays the analysis result and whether the determination result is good or bad.
Note that, as a reference of the related art, Japanese Patent Laid-Open No. H10-21267 (pages 6-15, FIG. 1) is known.
However, in the conventional electronic circuit analyzing apparatus, only the analysis result and the good/bad determination result thereof are notified, and decisions regarding the type of input information to be used to create the analytic model, and whether to perform analysis taking into account signal waveform variation caused by manufacturing irregularities in the element and electrical board, voltage fluctuation in the power source and ground, and so on are left to the user of the electronic circuit analyzing apparatus.
Moreover, since the accuracy and reliability of the analysis result are heavily dependent on the input information, it may be impossible to obtain a correct analysis result due to insufficient input information, low input information accuracy, and so on.
Further, since the type and accuracy of the input information required when performing analysis vary according to the operating conditions of the electronic circuit (operational frequency, output characteristic of the element, I/O buffer, internal resistance of the element, and so on), specialist capabilities are required to perform analysis with a high degree of reliability value. Hence the reliability value of the analysis result depends greatly on the capability of the designer, leading to irregularities in the design quality of products designed on the basis of the analysis result.
Furthermore, it is time-consuming to gather and measure accurate input information, and hence to shorten the design period, input information must be suppressed to a minimum while maintaining the reliability value of the analysis result.